Analysis of two-leg three-phase transformer-less PV inverter with corner grounded source

This paper presents the characteristics of two-leg three-phase (2L3P) inverter as a photovoltaic (PV) system by comparison with three-leg three-phase (3L3P) inverter. 2L3P inverter which has merit in the reduced number of power switches has been often used in V-V connected or special grid environments. However the inverter is also advantageous where it is applied in the transformer-less PV system because of its structural feature in leakage path. The feature depends on the output filter which is located between switch-less leg and the grid. Hence, in this paper, 2L3P inverter is analyzed and discussed for transformer-less PV topology. Its leakage path and resonance are analyzed in terms of output filter design, and topological characteristic is also presented. In experiments, 2L3P and 3L3P inverters are performed in both cases of 2-level and 3-level. Experimental results of the prototype circuits are shown to compare their performances such as rms value of the leakage current.